Field
The present invention relates to integrated circuits and, more particularly, to a thermal metal ground for cooling integrated circuit resistors.
Background
Some integrated-circuit resistors operate with high power dissipation. This leads to heating in the area of the resistor. The resulting increased temperature can impair the reliability of circuit elements in that area. For example, metal interconnect lines that are routed over the resistors could suffer from increased electromigration. Additionally, integrated circuit fabrication processes have scaled to smaller and smaller feature sizes. This leads to the possibility of increased power density and temperature rises in localized areas.
Resistors used for on-die termination (ODT) of inputs and outputs of an integrated circuit are an example of resistors that may have a high power dissipation. Some previous designs have lessened the temperature increase by making the resistors physically larger (increasing both the width and length of the resistor so that the electrical resistance is unchanged). Some previous designs have not used the area near the resistors for routing metal interconnects. Both of these approaches are undesirable as they result in a larger integrated circuit.